Princess Masuko (増子女王)

The Pricess Masuko (November 28, 1711- November 9,1733) was the legal wife of Ieshige TOKUGAWA, the ninth Shogun of the Edo bakufu (Japanese feudal government headed by a shogun). She was the fourth princess of the Imperial Prince Fushiminomiya. Her childhood name was Naminomiya.
Her honorific Buddhist title was Shomyoin
Her name is also written as 培子 or 増子 in Kanji characters. The Princess Sananomiya Masako, the legal wife of Yoshimune TOKUGAWA was her aunt.

She married Ieshige in 1731, moved into nishi no maru (a castle compound to the west of the main compound) of Edo-jo Castle, then she was addressed Gorenchu-sama (the legal wife of the heir to the Shugun). In 1732, Ieshige and she cruised down the Sumida-gawa River.

Although Masuko became pregnant in 1733, she lost the baby due to premature birth on October 18 (The child died soon after the birth.)
She did not recover from the postpartum, and died at the age of 23 on November 9 of the same year. Masuko was buried at Kanei-ji Temple, and was posthumously conferred the the court rank of Junii (Junior Second Rank). Her posthumous Buddhist name was 証明院智岸真恵大姉.

Masuko was never addressed as Midaidokoro (the title used for the wife of a shogun), because she died before Ieshige became the shogun.